1. Field of the Invention
The present invention relates to the structure of an electronic clinical thermometer with a soft flexible casing.
2. Description of the Prior Art
In recent years, electronic clinical thermometers wherein a thermistor is used as a temperature sensor and the temperature is converted in an electronic circuit and displayed by a liquid crystal display element have become widely available on the market.
An electronic clinical thermometer offers many advantages over the conventional mercury clinical thermometer, inasmuch as it does not break when dropped, the digital display si easy to read, there is no need to shake down the mercury level before use, and the like. In addition, with the electronic clinical thermometer it is possible to utilize a shape and materials conducive to easy reading of the temperature, as opposed to a mercury thermometer which must be enclosed in a glass rod to ensure that the mercury is visible.
For example, an oral measurement can be easily made without causing discomfort to the patient if the probe section is formed from a soft flexible material, providing a shape that is well-fitted to the mouth. Accordingly, such as electronic clinical thermometer has been disclosed in Japanese Laid Open Patent Application No. 61-76334. An embodiment of that invention is illustrated in FIG. 1. This thermometer comprises a flexible probe 26 which covers a thermistor lead wire, and a reinforcing plate 23, a circuit substrate 24, and a cover 25 which are securely connected by means of a plurality of screws 22 to a housing section 21 integrally formed in series with the probe 26.
However, the conventional electronic clinical thermometer disclosed in the above-mentioned application has the following drawbacks:
(1) The housing 21 and the cover 25 which are made from a flexible material are secured merely by elastic engagement so that the housing easily peels away.
(2) The reinforcing plate 23, the circuit substrate 24, and the cover 25 are secured to the housing only by the screws 22, so that the connection lacks stability because it is difficult to obtain an adequate securing force in a lapped flat seam in soft material.
(3) Because the electronic circuit part is not completely watertight, the cleaning and sterilization standards required for use in oral measurement cannot be attained.